ASCII 圖像中的垂直正則表達(dá)式匹配

問題

在 ASCII 圖像中，例如：

....X.......
..X..X...X....
X.X...X..X.....
X....XXXXXX.....
X..XXX...........
.....X..........
..............X
..X...........X....
..X...........X....X...
....X.....

我們'我想找到一個(gè)由三個(gè) X 組成的簡單垂直線結(jié)構(gòu)，而不使用除正則表達(dá)式之外的最佳方法。

問題 1：這種結(jié)構(gòu)是否存在

確定 PCRE/ 中是否存在這樣的結(jié)構(gòu)PHP、Perl、.NET 或類似的正則表達(dá)式，我們可以使用以下表達(dá)式：

(?xm)                    # ignore comments and whitespace, ^ matches beginning of line
^                        # beginning of line
(?:
    .                    # any character except \n
    (?=                  # lookahead
        .*+\n            # go to next line
        ( ?+ . )       # add a character to the 1st capturing group
        .*+\n            # next line
        ( ?+ . )       # add a character to the 2nd capturing group
    )
)*?                      # repeat as few times as needed
X .*+\n                  # X on the first line and advance to next line
?+                     # if 1st capturing group is defined, use it, consuming exactly the same number of characters as on the first line
X .*+\n                  # X on the 2nd line and advance to next line
?+                     # if 2st capturing group is defined, use it, consuming exactly the same number of characters as on the first line
X                        # X on the 3rd line

問題 2：計(jì)算此類形式

簡單匹配
For直接匹配并要求計(jì)數(shù)為匹配數(shù)，由于lookbehind支持有限，這個(gè)問題無法在PCRE或Perl中直接解決。

長度/間接解決方案
但是，如果答案被接受為匹配或替換的長度，然后可以用以下表達(dá)式回答：

^
(?:
    (?:                   # match .+? characters
        .
        (?=               # counting the same number on the following two lines
            .*+\n
            ( ?+ . )
            .*+\n
            ( ?+ . )
        )
    )+?
    (?<= X )              # till the above consumes an X
    (?=                   # that matches the following conditions
        .*+\n
        ?+
        (?<= X )
        .*+\n
        ?+
        (?<= X )
    )
    (?=                   # count the number of matches
        .*+\n
        ( ?+ . )        # the number of matches = length of 
    )
)*                        # repeat as long as there are matches on this line
.*\n?                     # remove the rest of the line

以上是您可以使用正則表達(dá)式在 ASCII 圖像中找到由三個(gè)'X”組成的垂直線嗎？的詳細(xì)內(nèi)容。更多信息請關(guān)注PHP中文網(wǎng)其他相關(guān)文章！